There may be many reasons why this person suddenly doesn't reply to your comments. Here are some possible reasons:

1. This person may be busy and has no time to reply to your comments.

2. He/she may not want to communicate with you or keep a distance from you.

It may be because of some misunderstanding or unpleasant things that he/she doesn't want to communicate with you anymore.

It may be because of network problems or other technical problems that he/she can't reply to your comments.

For whatever reason, if you really care about this person, you can try to communicate with him/her and ask if there are any questions. However, you should also respect each other's wishes. If he/she doesn't want to communicate with you, respect him/her and keep your distance.